WASHINGTON - As the Syrian regime and opposition trade accusations over the use of chemical weapons, the drumbeat in Washington for the United States to get more directly involved in the two-year old conflict is growing louder.

Republican Senators Lindsey Graham and John McCain released a statement today, calling for President Obama to act against Syrian President Bashir al-Assad.

State Department spokeswoman Victoria Nuland said the U.S. was looking into claims that the Assad regime had used a chemical weapon in a recent attack in the opposition stronghold of Aleppo. She would not confirm whether the administration believes Syria's chemical stockpile is secure, citing intelligence reasons, but said there continues to be an increasing concern that Assad will cross that line.

"We've been very clear about our concerns that the Assad regime is increasingly beleaguered, that it finds that the violence that it is using by conventional means is inadequate, including its barbaric use of Scuds. And so we are quite concerned that they will resort to other weapons," she said. "We've made clear that this would constitute a red line for the United States. The president could not have been clearer about it."

But Graham and McCain argue that Assad has likely already crossed the line and they want to see action taken.

"President Obama has said that the use of weapons of mass destruction by Bashar Assad is a 'red line' for him that 'will have consequences,'" the statement reads. "If today's reports are substantiated, the President's red line has been crossed, and we would urge him to take immediate action to impose the consequences he has promised."

The senators are calling for the United States to provide arms to vetted rebel fighters, to launch targeted strikes against Assad's aircraft and SCUD missile batteries on the ground, and to establish safe zones inside Syria to protect civilians living in opposition controlled areas.

Graham and McCain said time was not on the side of the administration to make sure Syria's chemical weapons cache does not fall into the hands of terrorists. Graham told Foreign Policy's The Cable that securing Syria's chemical weapons needs to be America's top priority, even if it means sending in U.S. troops to do it.

"I don't care what it takes," Graham said. "If the choice is to send in troops to secure the weapons sites versus allowing chemical weapons to get in the hands of some of the most violent people in the world, I vote to cut this off before it becomes a problem."

Foreign Policy also reported that the top Senate Democrat on the Armed Services Committee, Carl Levin, is now in support of establishing a no-fly zone in Syria.

"I believe there should be the next ratcheting up of military effort and that would include going after some of Syria's air defenses," Levin said.

America's European allies Britain and France have called for lifting the UN arms embargo against Syria so that they can legally provide more direct weapon and ammunition help to Syria's opposition army. Britain announced last week that it will begin proving armored trucks and body armor to rebel fighters.

Secretary of State John Kerry told reporters Monday that the Obama administration is still unwilling to provide anything more than the non-lethal assistance the U.S. is already giving, but will not oppose the actions of other governments.

"President Obama has made it clear that the United States does not stand in the way of other countries that have made a decision to provide arms, whether it's France or Britain or others," he said.

Kerry acknowledged, however, that the danger of Syria's chemical weapons falling into the hands of radicals on both sides of the conflict is growing.

"We have consistently said, and I say again, the longer the bloodshed goes on, the greater the prospect that the institutions of the state of Syria implode, and therefore the greater the danger is to the region and the world that chemical weapons fall into the hands of really bad actors," he said.

Kerry called the two-year conflict, which has killed an estimated 70,000 people and produced nearly 1 million refugees, a "global catastrophe," admitting that the status quo is not working.

"So as long as President Assad continues to attack his own people with Scuds, with aircraft, with tanks, there is an imbalance in this," Kerry said. "If he believes he can shoot it out, Syrians and the region have a problem and the world has a problem."